Publication Date:
2017-04-04
Description:
A stochastic triggering (epidemic) model
incorporating short-term clustering was fitted
to the instrumental earthquake catalog of Italy
for event with local magnitudes 2.6 and greater
to optimize its ability to retrospectively forecast
33 target events of magnitude 5.0 and greater that
occurred in the period 1990–2006.
Description:
A stochastic triggering (epidemic) model
incorporating short-term clustering was fitted
to the instrumental earthquake catalog of Italy
for event with local magnitudes 2.6 and greater
to optimize its ability to retrospectively forecast
33 target events of magnitude 5.0 and greater that
occurred in the period 1990–2006. To obtain an
unbiased evaluation of the information value of
the model, forecasts of each event use parameter
values obtained from data up to the end of the
year preceding the target event. The results of the
test are given in terms of the probability gain of
the epidemic-type aftershock sequence (ETAS)
model relative to a time-invariant Poisson model
for each of the 33 target events. These probability
gains range from 0.93 to 32000, with ten of the target
events yielding a probability gain of at least 10.
As the forecasting capability of the ETAS model
is based on seismic activity recorded prior to the
target earthquakes, the highest probability gains
are associated with the occurrence of secondary mainshocks during seismic sequences. However,
in nine of these cases, the largest mainshock of
the sequence was marked by a probability gain
larger than 50, having been preceded by previous
smaller magnitude earthquakes. The overall evaluation
of the performance of the epidemic model
has been carried out by means of four popular
statistical criteria: the relative operating characteristic
diagram, the R score, the probability gain,
and the log-likelihood ratio. These tests confirm
the superior performance of the method with respect
to a spatially varying, time-invariant Poisson
model. Nevertheless, this method is characterized
by a high false alarm rate, which would make its
application in real circumstances problematic.
Description:
This work was partially supported
for the years 2005–2007 by the Project S2—Assessing
the seismogenic potential and the probability of strong
earthquakes in Italy (Slejko and Valensise coord.)—S2
Project has benefited from funding provided by the Italian
Presidenza del Consiglio dei Ministri—Dipartimento della
Protezione Civile (DPC). Scientific papers funded by DPC
do not represent its official opinion and policies. The
authors are grateful to the Editors, Laura Peruzza, and
David Perkins, and to two anonymous reviewers, for their
comments and suggestions that contributed to a significant
improvement of the paper.
Description:
Published
Description:
9-26
Description:
3.1. Fisica dei terremoti
Description:
JCR Journal
Description:
reserved
Keywords:
Epidemic-type aftershock sequence
;
Short-range forecasting model in Italy
;
04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
